TIMING CHARACTERISTICS (See Figures 2, 3 and 4):

PARAMETER

SYMBOL

MIN

TYP MAX

UNIT

CONDITION

SYNC Frequency

40

-

70

Hz

-

SHORT Activation

50

-

417

ms

60Hz

60

-

500

ms

50Hz

LONG Activation

433

-

Infinite ms

60Hz

520

-

Infinite ms

50Hz

GATE DRIVE pulse width

GDW

2.31

-

7.13

ms

60Hz

(see Note 5)

GDW

2.78

-

8.56

ms

50Hz

Conduction Angle

ø

50

-

154

deg

-

Ø incremental steps

∆

ø

-

1.4

-

deg

-

(Note 1)

Soft-on slew rate

-

1.4

-

deg / 33.3ms 60Hz

-

1.4

-

deg / 40ms

50Hz

A0 to A1/A2 to A0 slew rate

-

1.4

-

deg / 33.3ms 60Hz

(Note 2)

-

1.4

-

deg / 40ms

50Hz

A1 to B1/B2 to A2 slew rate

-

1.4

-

deg / 66.7ms 60Hz

(Note 3)

-

1.4

-

deg / 80ms

50Hz

B1 to B2 delay

-

500

-

ms

60Hz

(Note 4)

-

600

-

ms

50Hz

Note 1: Total number of steps = 77.

Note 2: Number of steps from A0 to A1, or A2 to A0 = 55.

Note 3: Number of steps from A1 to B1 or B2 to A2 = 21.

Note 5: For LS7637 when minimum ø is reached, dimming direction reverses only

if the LONG Activation is terminated and reapplied.

The difference among all versions of

LS7636 and LS7637

are:

LS7636 (LS7636FO)

Upon power-up, the Gate Drive output is Off.

(Upon power-up, the Gate Drive output is On at maximum

conduction angle.) When a LONG Activation is applied,

the dimming direction automatically reverses whenever

maximum or minimum conduction angles are reached.

LS7637 (LS7637FO)

Upon power-up, the Gate Drive is Off.

(Upon power-up, the Gate Drive is On at maximum conduc-

tion angle.) When a LONG Activation is applied, the dim-

ming stops whenever maximum or minimum conduction

angles are reached. In order to change dimming levels

from maximum or minimum, LONG Activation must be re-

moved and reapplied. The purpose of this feature is to al-

low the user to positively locate maximum and minimum

conduction angles.

LS7637 NOTE:

If the User applies a LONG Activation when the

Gate Drive Conduction Angle is within a "few" de-

grees of Maximum or Minimum, the Gate Drive

Conduction Angle can move to Maximum or Mini-

mum and stop without the User being able to ob-

serve a change in brightness. Therefore, the User

should be instructed that if no change in bright-

ness is observed in response to a LONG Activa-

tion, the LONG Activation should be removed and

reapplied in order to produce a change in bright-

ness.

7636-121906-2